Well-cementing apparatus



United States Patent Inventor Bobby G. Comeaux Marrero, La.

Appl. No. 857.305

Filed Sept. 12, 1969 Patented Dec. 29, 1970 Assignee The Dow ChemicalCompany Midland, Mich.

a corporation of Delaware WELL-CEMENTING APPARATUS 2,655,216 10/1953Baker et a1 166/156 3,102,595 9/1963 Fisher. Jr et al. 166/156 3,159,21912/1964 Scott 166/156 Primary Examiner-James A. LeppinkAttorney-Griswold and Burdick ABSTRACT: In the course of cementing wellcasing in place in a bore hole, a plug follows the cement down thecasing and sets against a sealing surface in the casing, such as acementing 5 Claims 4 Drawing shoe in the casing. When drilling out theplug and the sealing U.S. fa e after the ement has et [he often rotateslllt- Cl E21b33/16 the rotating drill bit, making difficulty for the bitto bite into Field of Search 166/15 the rubber plug.

291 This invention provides slots in the sealing surface which R r dmate with protuberances on the surface of the plug which face e erencese the sealing surface, whereby as the plug seats and is rotated UNSTATES PATENTS slightly, the protuberances lock in the slots and prevent2,071,390 2/1937 Crowell 166/155 further rotation ofthe plug.

54 3 I l; I 2 2 5 42 56 Z4- e s Z0 I I 1'0 52 a PATENTEU 0502919103550.683

INVENTOR. Boy 6 Comeoux WELL-CEMENTING APPARATUS BACKGROUND OF THEINVENTION This invention relates to well cementing apparatus, andparticularly to cementing plugs and the shoes, float collars and stageor fill collars in which the cementing plugs are seated.

When casing is cemented into a well, a latch down plug is injected intothe casing immediately following the cement slurry. The plug is followedby drilling mud which is pumped into the casing to force the cement andthe plug down the casing. When the plug reaches the stage collar, floatcollar or cementing shoe equipment, the latching apparatus enters anaperture in the equipment and locks the plug in place. The plug,therefore, has acted as aseparator and wiper as it traverses the easingbehind the cement and finally acts as a valve to shut off the orifice inthe collar or shoe and prevent return of the cement slurry back up thecasing.

When the cement has set it is often desirable to drill through thecollar or shoe to deepen or otherwise modify the bore hole. When theconventional plug and collar or shoe are used, difficulty is encounteredin drilling out the plug because the drill bit does not bite into therubber because the. rubber plug rotates with the drill bit.

Accordingly, a principal object of this invention is to provide animproved cementing plug and collar or shoe seating apparatus.

Another object of this invention is to provide an improved cementingplug and seating apparatus in which the plug is nonrotatable when inplace within the seating apparatus.

In accordance with this invention well cementing equipment comprising acementing plug and seating apparatus are provided wherein slots orgrooves are made in the upper face of the seating apparatus. Matingprotuberances or teeth are coupled to the bottom of the wiper plug tolock into the grooves or slots of the seating apparatus, thus preventingrotation of the plug.

The invention, as well as additional objects and advantages thereof,will best be understood when the following detailed description is readin connection with the accompanying drawing in which:

FIG. 1 is a side elevational view, partly broken away and in section, ofseating apparatus in accordance with this invention, as applicable foruse in a cementing shoe;

FIG. 2 is a sectional view taken along the line 2--2 of FIG.

FIG. 3 is a side elevational view of a cementing plug in accordance withthis invention; and

FIG. 4 is an inverted plan view of the cementing plug shown in FIG. 3.

Referring to the drawing, and particularly to FIGS. 1 and 2, there isshown a cementing shoe, indicated generally by the numeral 10,comprising a hollow cylindrically shaped outer wall part 12 havingthreads 22 on the inner wall of the upper part of the shoe 110, a lowerpart 13 and a plate 16 extending transversely across the shoe betweenthe upper and lower parts. The plate 16 divides the shoe into twocompartments and has a central bore whose wall part 46 is a seat for thelower end part 62 of the plug 48 shown in FIG.3.

A cement plug receiving body part, indicated generally by the numeral20, is generally frustoconical in shape on its outer surface, the walladjacent to the base having threads which engage the threads 22. Thebody part 20 lies against the partition 16 and has a central bore 32aligned with and slightly larger in diameter than the bore in thepartition 16.

A frustoconically shaped counter bored part 28 forms a seat for thelower end part 50 of the plug 48 shown in FIG. 3 and extends from thetop 26 of the body part 20 to the grooved upper end part 30 of the bore32.

An array of arcuate slots 34,36,38, having the same radius of curvature,for example, and sloping in depth, is disposed in the body part 20extending inwardly from the surface 28 and usually symmetricallysurroundin the bore 32. A slot 40,42,44 extends from each of the sIots34,36,158 respectively. to the bore 32.

The above described shoe 10 is coupled to a length of casing 14 with theinner wall 24 of the casing fitting between the body part 20 and theouter wall part 12 of the shoe l0. A cementing plug, shown in FIGS. 3and 4, and indicated generally by the numeral 48, has a flared upper end68, a more or less semicircular lower end 62, an array of flexible wiperfins 66 a frustoconical seating surface 50 adapted to mate with thesurface 28, a downwardly extending shaft 58 having latching grooves 60disposed between its ends, and O-ring seal elements disposed adjacent tothe lower end 62 and adapted to bear against the unthreaded part of thewall of the bore 32. Embedded in and bonded to the frustoconical surfacepart of 50 of the plug 48 are an array of 3 arcuate shaped strips52,54,56 which extend downwardly from the surface 50 in longitudinalalignment with the slots 34,36,38. The length of the arcuate strips isless than the length of the slots 34,36,38, and the arcuate strips areadapted to mate with the slots 34,36,38.

In operation, the plug 48 is dispatched down the bore hole through thecasing 14 following the cement. The plug 48 is followed by usually mudor other pumpable fluid material.

When the plug 48 reaches the counter bored part 28, the strips or teeth52,54,56 settle into the grooves or slots 34,36,38, the lower end of the62 of the plug passing into the bore 32 and seating on surface 46 as thegrooves 60, 30 latch together.

After the cement has set and the plug is to be drilled out, the bit (notshown), in tending to rotate the plug, drives the teeth even deeper intothe grooves 34,36,38, with material in the grooves being forced outthrough the slots 40,42 ,44.

Thus, even though the bit rotates against the rubberlike top of the plug48, the plug cannot rotate and the bit drills through the plug and thenon through the seating apparatus.

The teeth 52,54,56 are usually made of metal, such as aluminum, forexample, which is embedded in and bonded to the rubberlike material usedin making the rest of the plug 48.

I claim:

I. Well-cementing equipment comprising a seating apparatus adapted to becoupled in a length of easing, said apparatus having a body partincluding a partially grooved axially disposed bore and afrustoconically shaped counterbore part on the end thereof facing theupper end of the casing, said frustoconically shaped part having anarray of arcuate slots disposed generally around said axially disposedbore, and a plug member having a frustoconical surface adapted to matewith said frustoconically shaped part of said apparatus, saidfrustoconical surface having an array of arcuate teeth extendingdownwardly therefrom in axial alignment with said arcuate slots andadapted to mate with said slots.

2. Well-cementing apparatus in accordance with claim 1, wherein alatching and sealing section extends below the frustoconical surface ofsaid plug.

3. Well-cementing apparatus in accordance with claim 1, wherein saidarcuate slots are of greater depth at one end than at the other.

4. Well-cementing apparatus in accordance with claim 1, wherein slotsextend between each of said arcuate slots and said axially disposedbore.

5. Well-cementing apparatus in accordance with claim I, wherein saidteeth are made of metal embedded in and physically coupled to a flexiblematerial.

